Re: PATCH: LDFLAGS handling in V3

[Mark Mitchell <mark at codesourcery dot com>]

Mark Mitchell wrote:

> If all target libraries are assumed to be built with libtool, then we 
> can indeed defer to the user. 

However, that is not the case.  For example, libiberty is not built with 
libtool.  Empirically setting LDFLAGS_FOR_TARGET to include a -Wc, 
option at the top level results in configure-target-libiberty failing, 
because configure tries to actually invoke the linker with the -Wc, 
option, which it doesn't understand, resulting eventually in:

checking for library containing strerror... configure: error: Link tests 
are not allowed after GCC_NO_EXECUTABLES

because an earlier link command has failed.

> I do  understand what you mean about quoting and about reusable scripts.
>  I suppose I could work on that, once we know what we want it to do.

So, I think we have to go this route.

Therefore, I thought about writing a script which, when invoked as 
"libtool-ldflags $(LDFLAGS)" outputs a string that will look like:

  -Xcompiler flag1 -Xcompiler flag2

where flagN is properly quoted, so that you can do:

  eval libtool --mode=link ... `libtool-ldflags $(LDFLAGS)`

(Alexandre, I didn't want to use -XCClinker because the GCC version of 
libtool doesn't have that, but that's a detail.)

However, this doesn't seem like it would work well, because of the need 
for "eval", which means that other options on the link line might get 
mangled.  In GNU-make, we could do:

  LTLDFLAGS := `libtool-ldflags $(LDFLAGS)`

and then:

  libtool --mode=link ... $(LTLDFLAGS)

which should work OK, since GNU make will evaluate the shell command 
early.  But, libstdc++ hasn't yet gone over to GNU make; it's still 
assuming plain automake, I think.  I don't really know how to solve this 
problem in that context.

I guess the best I can think of is to have the top-level Makefile add:

  "LTLDFLAGS=`libtool-ldflags $(LDFLAGS)`"

to EXTRA_TARGET_FLAGS.  Then, the sub-make files can just choose between 
LDFLAGS and LTLDFLAGS, depending on whether or not they're using 
libtool.  Does that sound like the right plan?

Thanks,

--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304